The scientific objective of this project is to utilize the vibrissal motor system (VMS) of rodents as a model for experimental studies of the facial muscles in the orofacial region. This will be accomplished by employing three representative species (golden hamster, rat, guinea pig) to test the general hypothesis that different types of orofacial behavior (e.g., different categories of vibrissal movement) reflect different patterns of neural organization of the facial muscles. One specific aim is designed to test the general hypothesis regarding likely levels of organization. The general hypothesis is that homologous facial muscles with dissimilar functions have dissimilar patterns of neural organization. To test this, Specific Aim (1) is to determine the fiber type composition of the vibrissal facial muscles in each species via both enzyme histochemical and immunocytochemical methods, and to compare the three species. A VMS model of the facial musculature would provide new information on the functional properties of facial muscles. This could be valuable clinically in forming the basis of understanding for (1) applied studies of steroid therapy for treatment of facial muscle injury, and (2) facial muscle response to individual muscle response to individual muscle and/or whole flap transposition for orofacial paralysis and/or reconstruction. The second objective of this project is to educate students in the life sciences, specifically, in research in the field of neuromuscular biology. To accomplish this, one undergraduate student will be trained in the context of the above study.